Preventing sick building syndrome comes down to controlling what’s in the air people breathe indoors: fresh air supply, moisture levels, chemical emissions from materials, and the overall design of the space. The World Health Organization estimates that 30% of new or remodeled office buildings show signs of sick building syndrome, affecting 10% to 30% of occupants. The good news is that most causes are manageable with the right choices during design, construction, and ongoing building maintenance.
What Sick Building Syndrome Actually Is
Sick building syndrome describes a pattern of symptoms, including headaches, eye and throat irritation, dry skin, fatigue, difficulty concentrating, and nausea, that cluster among people who share a building and improve once they leave. It’s not a single diagnosable disease. The symptoms are common on their own, but what flags SBS is that they appear excessively among occupants and are clearly tied to time spent in the building.
This is different from a building-related illness like Legionnaires’ disease or hypersensitivity pneumonitis, where a specific pathogen or allergen causes clinically identifiable disease that can require prolonged recovery. With SBS, most people feel better shortly after leaving the building, and no single cause can be pinpointed. That vagueness makes prevention all the more important, because there’s no straightforward treatment once symptoms appear beyond fixing the building itself.
Bring in More Outdoor Air
Inadequate ventilation is the single most consistent factor behind SBS complaints. The current ASHRAE standard for office buildings calls for a minimum of 5 cubic feet per minute of outdoor air per person in occupied spaces, plus an additional rate based on floor area. In practice, many buildings fall short because HVAC systems are poorly maintained, dampers get stuck closed, or systems are deliberately throttled to save energy.
The case for generous ventilation goes beyond comfort. Research from Lawrence Berkeley National Laboratory found that when indoor carbon dioxide concentrations reached 1,000 ppm, a level common in under-ventilated offices, test subjects showed significant declines on six out of nine decision-making measures. At 2,500 ppm, performance dropped even further, with strategic thinking and initiative rated as “dysfunctional.” CO2 itself isn’t the only concern at those levels; rising CO2 is a reliable signal that other pollutants generated by people, furniture, and equipment are also accumulating.
Increasing outdoor air supply from low rates to around 30 liters per second per person has been shown to significantly improve simulated office work performance, with gains in the range of 6 to 9%. If you manage a building, start by verifying that your HVAC system is actually delivering the outdoor air it was designed to deliver. Sensors that track CO2 in occupied zones are an inexpensive way to confirm ventilation is working. Aim to keep CO2 below 1,000 ppm during occupied hours.
Upgrade Your Air Filtration
Ventilation alone isn’t enough if the air coming through the system carries dust, pollen, or fine particulate matter. The EPA recommends filters rated MERV-13 or higher, which can trap smaller particles including fine dust, mold spores, and even some airborne viruses. Many commercial and residential HVAC systems ship with MERV-8 filters as the default, which catch larger particles but let finer irritants pass through.
Before upgrading, confirm that your system’s fan and filter housing can handle a higher-rated filter. Denser filters create more resistance to airflow, and a system that wasn’t designed for them may strain or push air around the filter edges. A qualified HVAC technician can evaluate whether your system supports MERV-13 filters or whether supplemental air purifiers are a better option. Replace filters on schedule; a clogged MERV-13 filter performs worse than a clean MERV-8.
Control Humidity
The EPA recommends keeping indoor relative humidity between 30% and 50%. Below 30%, mucous membranes in the eyes, nose, and throat dry out, producing the irritation symptoms that define SBS. Above 50%, mold growth accelerates and dust mite populations thrive, both of which worsen respiratory complaints.
In humid climates, this means ensuring your HVAC system is properly sized for dehumidification, not just cooling. Oversized air conditioners cool air quickly but cycle off before removing enough moisture. In dry climates or during winter, humidifiers may be needed, but they require regular cleaning to avoid becoming contamination sources themselves. Portable hygrometers cost very little and let you monitor conditions in problem areas like windowless interior rooms or below-grade spaces where humidity tends to drift outside the ideal range.
Choose Low-Emission Building Materials
New or renovated buildings often have the worst SBS problems because fresh materials release volatile organic compounds at their highest rates. Formaldehyde is one of the most common offenders, released by pressed-wood products, certain adhesives, and some insulation materials. OSHA sets the permissible workplace exposure limit at 0.75 ppm over an eight-hour period, but building material standards aim much lower. The CHPS 01350 standard, widely used for healthy building certification, requires that materials emit formaldehyde at concentrations no higher than 16 micrograms per cubic meter (about 11 parts per billion), roughly half the lowest level considered achievable given background outdoor concentrations.
When selecting materials, look for these specific certifications:
- Paints: Choose 100% acrylic or low-VOC formulations. Avoid paints marketed as mold-resistant, as these typically contain biocide additives that can themselves irritate occupants.
- Flooring: Carpets carrying the CRI Green Label Plus mark have been emission-tested to meet CHPS 01350 VOC limits. For hard flooring, the FloorScore certification covers resilient products like vinyl and laminate.
- Adhesives and sealants: Select products with the lowest available VOC emissions that still meet performance needs. Avoid adhesives containing formaldehyde entirely when alternatives exist.
Timing matters too. If renovation is unavoidable in an occupied building, schedule material installation during low-occupancy periods and increase ventilation rates for several weeks afterward to flush out the initial burst of off-gassing.
Reduce Indoor Pollutant Sources
Materials aren’t the only source of indoor air contamination. Everyday office equipment, cleaning products, and even occupant activities contribute. Laser printers and copiers emit fine particles and ozone; placing them in ventilated rooms separate from workstations helps. Cleaning crews that switch from solvent-based products to fragrance-free, low-VOC alternatives remove a common source of irritation.
Research has shown that simply removing common indoor pollution sources like old floor coverings, spent HVAC filters, and running electronics can improve office work performance by a measurable margin. This doesn’t require a major renovation. It means replacing carpet that’s past its useful life instead of letting it degrade, swapping out supply air filters before they become secondary pollution sources, and ensuring copier rooms and kitchenettes have dedicated exhaust ventilation.
Add Natural Elements to the Space
Biophilic design, the practice of incorporating natural elements into built environments, has measurable effects on stress, fatigue, and the subjective experience of indoor air quality. Views of greenery from windows have been linked to lower blood pressure, better attention recovery, and improved mood. When window views aren’t an option, even interior plants, nature imagery, and natural materials can help.
Sound matters more than most people expect. Water sounds in particular serve double duty: they mask distracting speech noise (a major complaint in open offices) while reducing physiological stress and boosting cognitive performance. Studies in open-plan offices found that natural sound consistently helped people recover from fatigue and annoyance more effectively than silence or white noise, regardless of whether the visual environment was natural or not.
Combining multiple senses amplifies the effect. Research conducted in a living lab setting found that multisensory biophilic interventions, pairing visual nature elements with natural sounds or pleasant scents like lavender, reduced perceived stress more than any single element alone. These interventions are relatively inexpensive compared to mechanical system upgrades and can be layered on top of ventilation and material improvements.
Maintain Systems Over Time
Many buildings that perform well at opening develop SBS problems years later because maintenance lapses. HVAC coils collect biofilm, drain pans overflow or stagnate, filters go unchanged, and outdoor air dampers fail closed. A building’s ventilation system only prevents SBS if it’s actually running as designed.
Scheduled inspections of HVAC components, including coils, drain pans, humidifiers, and ductwork, should happen at least annually. CO2 monitoring in occupied zones provides real-time feedback on whether ventilation rates have drifted. Moisture intrusion from roof leaks, plumbing failures, or condensation on cold surfaces needs to be addressed within 24 to 48 hours to prevent mold colonization. And any new furniture, equipment, or materials brought into the space should meet the same low-emission standards used during original construction.
Prevention is not a one-time project. It’s a combination of good initial design choices and ongoing attention to the systems and materials that determine what people breathe every day.